Vitamins A, B, and C have all had their turns in the spotlight. Now it’s time for the elusive and misunderstood D to have its turn at stardom.

For years, vitamin D was simply calcium’s escort, helping it move from the stomach through the blood stream and then into the bones. But now, we are starting to understand its true colors - and what a rainbow of tasks it performs.

Turns out, vitamin D is involved in nearly every single vital function of our body – from cell renewal, insulin production, and immune system function. Deficiencies of the vitamin have been linked to autism, cancer, depression, osteoporosis, heart disease, hypertension, autoimmune disorders, and chronic fatigue.

The scariest part of all is that most of us are not getting enough of it. According to a report in the Archives of Internal Medicine, up to 77 percent of Americans are vitamin D deficient.

So where does vitamin D come from and how can you up your dose? It’s actually not so straightforward. Sunlight converts a substance found in our skin to vitamin D naturally. However, to get enough of it, you would take in 15 minutes of midday sun on most of your body. But to do that would mean exposing your body to cancer-causing UV rays, something none of us should risk.

To make matters even more complicated, it’s not in many of the foods we eat. Some fish and fortified dairy products may have it, but the best way to get your recommended 1,000-plus IU a day is to take a supplement. That's right - after all the talk of that it’s better to get your nutrients from a balanced diet, there’s an exception to the rule. But luckily, vitamin D supplements are an easy, inexpensive way to make sure you are getting the minimum daily dose.

So pop your pills – all those D’s add up to grade-A health.